There exists a well recognized need worldwide to increase the use of renewable energy sources and reduce the amount of fossil fuels consumed in energy production.
There are a number of barriers to the increased use of renewable energy. The major barriers are that renewable energy sources are, in the main, costlier than other energy sources, are not available at the times required and are of variable quality. Hence there exists a need for regulating systems which can help bridge the time gap between availability and demand and also maintain the quality of the electricity produced from renewable sources. In this way the renewable energy would become more inherently valuable. Adding value to renewable energy by improving its quality and making it available on demand would substantially help to overcome the higher capital cost of systems and the cost of production. This would then facilitate the increased use of renewable sources.
Currently, solar power systems fall into two categories:—
1) Photovoltaic (PV) systems, in which solar energy is absorbed into materials that convert the suns rays directly into electricity;
2) Concentrating Solar Power (CSP), in which solar energy is used to heat a fluid and that heated fluid is used to directly or indirectly drive a mechanical device (such as a turbine) to convert the heat energy into electrical energy. To enable solar radiation to be used as heat for a thermodynamic cycle to produce process steam or electricity, it must be first concentrated to achieve higher temperatures, as solar radiation reaches the earth at a density too low to produce such temperatures.
Systems currently in use include:—                Trough type linear collector systems, which comprise a linear reflector, parabolic in cross, section, and one collector tube running along the focal point of the parabola in each reflector. This tube contains a fluid which is heated. The heated fluid is then pumped to a heat engine (e.g. a turbine) which it drives directly (if the collector fluid is water/steam) or through a heat exchanger (if the collector fluid is oil);        “Fresnel” type linear collector systems, which comprise multiple flat linear reflectors, all at different angles, to simulate a large parabolic shape with one collector tube set high above the multiple reflectors also collecting energy in a fluid in the tube as above.        
It is a feature of these linear systems that maximum temperatures consistently achievable are in the range of 350° C., which means that the heat engines operate at low efficiency levels, i.e. in the 250° C. to 300° C. range.
In order to achieve higher temperatures, and to be able to run more efficient heat engines, systems in use include:                Single High Towers which collect solar energy concentrated to a target from a large number of flat mirrors which track the sun and focus the large number of images at one collection point, where the high temperatures achieved are used to heat a fluid which is transmitted to an engine and converted to electricity;        Dish/Engine systems, where a small heat engine is placed at the focal point of a parabolic dish and driven directly by the concentrated solar energy;        Multi tower solar thermal systems where a number of smeller towers are used to collect the solar energy in a similar way to the high towers, but the mirrors can also be curved, so that the concentration of the energy is much greater and high temperatures (over 1000° C.) are achieved with less mirrors per tower.        
In each of these systems the solar energy if not used immediately has to be used as it is collected or the hot fluid conveyed away to a fluid based storage system, such as hot water, steam or molten salt, or a solid based storage system, such as hot rock, concrete or sand.